Various embodiments of hand-held devices are provided for piercing for puncturing a human or animal skin. A substance may be introduced into the skin or underlying tissue in conjunction with the piercing process. Such an introduction takes place for example when using a syringe as a hand-held device, with a substance to the applied being introduced through the cannula of the syringe after the piercing operation. The introduction of a substance into the skin also takes place in conjunction with the production of tattoos or permanent makeup. In this case, the skin is punctured in order to then introduce an ink into the skin layers. In conjunction with other medical or cosmetic applications however, it may also be that a substance, for example a cosmetic or a medical active ingredient, is introduced into the skin and/or underlying tissue in conjunction with the piercing process. One field of application in this area is mesotherapy.
Different substances often require a different piercing depth when piercing the needle of the hand-held device into the skin. For example, the effect to be developed of the introduced substance can be optimised by means of a suitable piercing depth. A further action is the stimulation of the skin by means of piercing the skin, for example for the treatment of wrinkles or for the treatment of scars. These treatments can also be carried out without the insertion of any substance. The capacity to adjust the piercing depth is of significance here in order to reach the desired skin layer. If the piercing is too shallow, the desired results will not be provided. If the piercing is too deep, excessive trauma will be caused.
To vary the piercing depth, it has been proposed for example to vary the stroke performed by the needle of the hand-held device. The length via which the needle protrudes with respect to a front housing opening, for example the opening in a needle jet, at the end of the extension movement is then adjustable as a result. This type of piercing depth adjustment requires an adjustment mechanism for stroke adjustment and is therefore routinely complex.
In the case of tattoo and permanent makeup devices, a needle protrusion can also be adjusted by changing the distance between a front needle jet opening and the needle tip in the extended position of the needle. In document EP 2 388 033 A1 it has been proposed, similarly to this principle, to arrange an attachment part on a syringe that is to be manually actuated, the axial length of the attachment part being adjustable by fitting a front component via a screw thread onto a base component, such that, by means of rotation of the front component, the length of the attachment part is adjusted on the whole. The length of the cannula by which the cannula protrudes beyond the distal end of the attachment part is thus ultimately adjusted. The piercing depth for the cannula of the syringe can thus be adjusted. The adjustment of different lengths of the attachment part means that the front part and the base part are mechanically coupled to one another to a different extent. The region of overlap between the front part and the base part is shorter, the further the front part is unscrewed in order to reduce the piercing depth. The reduction of the overlap between the two components is not advantageous for the mechanical stability of the connection between the components.
A tattoo device is known from document EP 2 454 966 A2, in which a stroke performed by the piercing needle is adjustable. To this end, recesses offset from one another in the axial direction are provided on a connecting rod and a protrusion on the needle shaft engages into the recesses, wherein different needle strokes are implemented by means of engagement in different recesses. The piercing depth changes according to the needle stroke.
A hand-held tattoo device is also known from document EP 1 992 387 A2. Documents U.S. Pat. No. 4,990,135, WO 2012/029082 A1 and also EP 2 388 033 A1 relate to syringes with which a needle length protruding beyond the front housing tip is variable.